It is standard practice in commercial chicken and turkey hatcheries to inoculate day-old birds so as to protect them from the many infectious diseases which affect mortality and meat quality. The principal method of inoculation has been to manually inject the young birds with a suitable antibiotic or vaccine using a hypodermic needle and syringe.
Another method of inoculation that is being employed now by most turkey hatcheries is to dip hatching eggs in an antibiotic solution prior to incubation. This is done mainly to combat a disease peculiar to turkeys known as Mycoplasma Melangridis (MM) and to help control other detrimental organisms which could affect the percentage of eggs hatched and the chances of survival after hatch.
In dipping, a temperature differential or vacuum is used to force the antibiotic solution through the shell of the egg. Although the benefits derived from this method make its use worthwhile, there is very little control of the dose volume. This is due to varying shell porosity and thickness. Thus, some eggs receive too much antibiotic, causing toxic embryonic death, and others do not receive an amount sufficient to be effective.
A method of egg inoculation prior to incubation which eliminates the problem of precise volume control associated with dipping involves the use of a hypodermic needle and syringe to inject known quantities of antibiotic into the eggs by hand. The operator uses a drill or other instrument to make a small hole in the shell and then inserts a hypodermic needle through the hole and injects a precise amount of solution into the egg. After the needle is retracted from the egg, the hole is sealed with a wax or cement. This is a slow and meticulous process which is very labor intensive, expensive and subject to human error.
Recognizing the need to be able to inoculate baby turkeys while the turkeys were still in their eggs, and further recognizing the ineffectiveness and inefficiency of the prior apparatus and methods for performing such immunizations, I invented an automatic egg injection machine and method which is patented in U.S. Pat. No. 4,040,388, issued Aug. 9, 1978 and entitled "METHOD AND APPARATUS FOR AUTOMATIC EGG INJECTION".
In devices according to this patented invention, a plurality of eggs resting in a tray having an apertured bottom are injected from below by a plurality of vertically disposed needle assemblies carried by a vertically movable injection device. In an up or injection position, the needle assemblies abut the lower ends of the eggs. When the needle assemblies are first brought into abutment with the eggs, heating elements in the needle assemblies are activated to sterilize portions of the shells. Next, each individual needle is moved upwardly out of its respective needle assembly so as to puncture the shells at the sterilized areas. A separate drive means is provided for each needle. Subsequently, the liquid vaccine is injected through the needles, the needles are withdrawn and the heating elements are activated to coagulate the albumin at the location of the injection holes so as to seal the holes.
It soon became apparent that this method and apparatus had certain limitations and risks involved with the use thereof. Therefore I invented yet another egg injection method and apparatus, with Perry Sheeks, which is the subject of U.S. patent application Ser. No. 383,839, filed June 1, 1982 and entitled "EGG INJECTION METHOD AND APPARATUS".
The egg injection devices according to that invention employ multiple needle assemblies fixed to a common vertically-movable needle plate to inject a tray of eggs. The needle plate and assemblies are located beneath the tray of eggs and inject the eggs through the bottom of the tray. The needle plate is accelerated rapidly upwardly by a single drive device thereby simultaneously moving all of the needle assemblies. The needles impact the eggs at a high velocity, the penetrating ends of the needles acting as cutting dies that cause small circular discs the same diameter as the needles to be sheared away from the shell. After the needles enter the egg, the needle plate engages a shock absorber system that slows the needle plate to zero velocity over a short distance (typically 1/8"), without subjecting the eggs to damaging shock. The injection fluid is then passed through the needle assemblies and injected into the eggs. This feature of multiple needles attached to a common needle plate enable an entire tray of eggs to be pierced and inoculated simultaneously.
The machines and methods of the invention disclosed in this pending application, as well as the machines and methods according to U.S. Pat. No. 4, 040,388 are designed and function to inject the injection fluid into the smaller end of the egg.
However, there are instances where it is desirable to inject into the large end of the egg. For example, in one application involving chicken eggs, it is desirable to deposit a vaccine in close proximity to the nostrils of the developing embryo at the large end of the egg. Specifically, the chicken industry currently injects manually over 4 billion day old chickens each year with a vaccine to control what is called Merek's disease. It takes a few days for the vaccine to become effective and a percentage of the chicks that are exposed soon after hatching still catch the disease. The United States Department of Agriculture has recently shown that by injecting the eggs 3 days prior to hatch, the chicks are protected from Merek's disease by the time they hatch so they overcome early exposure to the disease much better than chicks vaccinated at hatching.
The embryo vaccination work by the United States Department of Agriculture was performed by hand and, as such, was very labor intensive and expensive. I therefore became aware of the need in the industry for an egg injection machine and an injection method which would vaccinate eggs through their larger ends automatically and more economically as compared to the hand injection method.
This invention fulfills this need in the art, and other need will become apparent to the skilled artisan once given the following disclosure: